US2893364A - Fuel injection system for an internal combustion engine - Google Patents

Description

July 7, 1959 c. M. ELLIOTT ETAL 2,393,364

FUEL INJECTION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE 5 Sheets-Sheet 1 Filed April 10, 1956 VENTORS. 67170 071 f; Z'ZZzaZZ gear] .5. A a/2 ,yrra FIVE/Sf July 7, 1959 c. M. ELLIOTT ET AL 2,893,364

FUEL INJECTION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE Filed April 10, 1956 5 Sheets-Sheet 2 INVENTORS CZi/i o 71 M JZZz'a/E.

WAJQL- irraxwz/s' July 7, 1959 c. M ELLIOTT ETAL 2,893,364

FUEL INJECTION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE 5 Sheets-Sheet 3 Filed April 10, 1956 d a w 7. S J i M, A m z W /IA I /WWMWZ/ NH a, i m W WA]; fi a 11 M N 0/ J z m i m A. J v w 4 I 4 z y 1 r u I 5 .1 W "M w h mwmk ufi I 4 72 4 .1 U; 2 w? a. B Z I 0 n :M a m v a .w\m g RMUKU i z a a M J July 7, 1959 C. M. ELLIOTT ET AL FUEL INJECTION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE Filed April 10, 1956 5 Sheets- -Sheet 4 V EN TORS 677/2271 )9 zzzzbzz.

gear? J? #07 71 July 7, 1959 c. M. ELLIOTT ETAL 2,893,354

FUEL INJECTION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE Filed April 10, 1956 5 Sheets-Sheet 5 VENTORS 672/7071 IZZzaZ FUEL INJECTION. SYSTEMFOR AN COMBUSTION ENGINE,

Clifton M. Elliott and, Mearl ,E. Noftz, Birmingham, Mich, assignors to Chrysler Corporation, Highland Park, Mich., a corporation of Delaware:

Application April 10, 1956,'S,erial,N0.:577,'6 27 2'5-Claims, (ClL' 123-"-1-19)-' Our invention relates generally to a fuel system for an internal combustion engine andymore particularly to a new and improved-fuel injection system which is particularly adapted to be usedwith'spark' ignition engines and which is characterized by low operating fluid pressures.

Afuel injection system of the general type referred to above has been disclosed in the copendingpatent-application of Jorma O. Sarto, Serial No. -460;668-,: filed Octobe'r-6, 1954, .which is assigned to the assignee-of-ourinstan-t invention. Many of the constituent elements of the fuel system of the present'invention are disclosed-in .the above-identified copending application. However,- this application is a continuation-in-part of our-copendingapplication Serial No. 504,577, filed April'28',-1955', now abandoned, and relates to-a fuel system having new-and improved speed sensor and load sensor units of simplified construction'cooperable' to provide a controlled supply ofliquid fuel to the air atomizing nozzles associated with the engine cylinders.

The operating pressures of the fuel system:of our instant invention are of a low-order or magnitude in. comparison with the operating pressures of fuel: injection systems of known construction. Asseparate nozzle is providedfor each of the. engine cylinders andtbyvpreference, a separate intake air conduit-tor ram tube .is provided for each of the engine cylinders. An air distribution chamber is provided for supplyingeach oftheram tubes with a uniform inlet air supply.

The: provision of an improvedfuel'injection system being a principal object of our instant invention, further objects are to provide needle valve controlled load sensor and speed sensor units of improved construction, .the. load sensorxunit being characterized. by. improvedresilient means for-biasing the needle valve, in accordance .withthe engine load requirements/the speedlsensor unit vcomprising a unique! and highly efli'cient-mechanicalgovernor means cooperable with the load sensornnit for adjustably positioning the needle valve of the speedzsensor unit to assure optimum fuel delivery at substantially alliengine speeds.

Itis-a further object of our instant invention toprovide a speed sensor of the type referred to above'wherein the adjustable needle valve element, the flow. restricting orifice,.. and the mechanical governor .meansareconcentricallyarranged ina compact, efiicientarrangement.

It is a further object of our instant invention to provide a speed sensor for use-witha fuel injection system as setforth above, wherein said adjustable needlevalve is carried by a movable diaphragm, and wherein fluid passage means are provided for subjecting said diaphragm to =the pressure drop-across'the flow metering orifice associated with the load sensor unit.

It is a further object of our instant invention to-providev anew and improved means for-sealingthe fluid pressure which is. disposed across the movable diaphragm of the-speed sensor unit-referred torin-';the:preeeding object.

Still another object. is to provide an improvedfuel metering system ofthe above character comprising ,co-. operatingload sensor. and speed sensor unitsin series.

and improved means for adjusting the needle valve., of the speed sensor unit to control the flow of fluid to the,

tire fuel injection system pf whichrthe speed sensorunit of our instantinvention forms a part;

Figure 2 is a cross sectional view of a starting unit. Which-forms a portion of thefuel injection system shown in Figure l;'

Figure 3 is across sectional viewof a load sensor metering mechanism which forms a portion of the fuel system of Figure .1;

Figure 3A is. a graphic representation of the relation-. ship between enginemanifold pressure and engine power and fuel delivery through the load sensor orifice;

Figure 4 is a cross sectional view showing the detail, construction of the speed sensor unit of our instantiavention, said speed sensor unit being adapted to be used with the fuel injection system of Figure 1;

Figure 4A is an enlarged fragmentary schematic view of a portion of the governor mechanism of Figure 4, illustrating the relationship between the locations of the centers of gravity and pivot axes of the governor weights and their engagements with the actuating means for speed sensor needle valve;

Figure 5 is a plan view of an engine-powered fuel and air pumping unit which is adapted to be used with the fuel system of Figure. 1 for supplying a .plurality of air atomizing nozzles with a supply of liquid fueland air;

Figure .6. is a crosssectional view of the upper portion of the fuel and air pumping unit of Figure 5 and taken along section line 6-6 of Figure 5;

Figure 7-is a vertical cross sectional view of the fuel and air pumping unitpof Figure 5 and is taken along section line 77 of Figure ,5;

Figure- 8 isa view showing a portion of the check valve system for the airpumping portion of the fuel and air pumping unit of Figure 5 as viewed along section line 8'- f Figure 7; and

Figure 9 is a cross sectional view of an accelerator pumping mechanism which is adapted to be used with and to forma POItiOD'Of thC fuel system of Figure 1.

Referring first to Figure l, the numeral 10 is used to generally designate the vehicle engine and it comprises a flywheel 12 powered by and coupled to an outwardly ex; tending --portion 14 of the engine crankshaft. The engine illustrated in Figure 1 is of a V-8 configuration having two banks of cylinders, as shown at 16 and 18, upon which are secured a cylinder head and manifold structure shownat 20 and 22 respectively. However, it will be apparent that the fuel injection system of our instant invention-is capable of being used with many other types of internal combustion engines including multiple cylinder in line" engines and opposed cylinder engines or the like. A plurality of individual intake conduits 24.are provided as shown with a separate conduitcommunicating with each of the plurality of engine cylinders.- The conduits, 24 function as ram tubes and their. lengths may be chosen so that the optimum ram effect may be obtainedthroughout the normal operating speed and load ranges of the engine. Each of the conduits 24 communicates -,with,an intake air distribution chamber or plenum chamber 26.- The chamber 26 maybe suppliedby onenr moreconduits- 2.8.:1which may-be connectedto an intake a ented Ju y ,1959

filter and cleaner assembly 30 situated at the upstream end thereof.

The principal components of the fuel injection system herein disclosed include a fuel and air pumping unit 32, a load sensor unit 34, a starting unit 36, an accelerator pumping mechanism 38, a check valve 40, a plurality of air atomizing nozzles 42, and a speed sensor unit 44. Suitable conduit structure is provided for interconnecting the various individual components of the fuel system, said conduit structure including a fuel delivery conduit 46 extending from the discharge side of the fuel pumping portion of the fuel and air pumping unit 32 to the speed sensor unit 44.

Another conduit 48 is adapted to conduct fuel from the speed sensor unit 44 to the inlet side of the load sensor unit 34. The fuel is then conducted from the load sensor unit 34 to each of the individual air atomizing nozzles 42 through a conduit50. An air delivery conduit 52 extends from the discharge side of the air pumping portion of the fuel and air pumping unit 32 to each of the individual air atomizing nozzles 42 as shown. The air pumping portion of the fuel and air pumping unit 32 is double-acting as will be subsequently explained, and it is therefore provided with a second air delivery conduit 54 which communicates with the air delivery conduit 52 to supply the air atomizing nozzles 42 with fuel atomizing air during the half cycle of the pumping operation when air is not delivered through the delivery conduit 52.

A bypass conduit 41 extends from the fuel delivery conduit 46 to the intake side of the accelerator pumping mechanism 38 and another bypass conduit 43 extends from the outlet side of the pumping mechanism 38 to the conduit 50. The check valve 40 is adapted to accommodate the flow of fuel from the pumping unit 38 into the conduit 50 and to prevent a back flow into the pumping mechanism 38 or into the load sensor 34. The accelerator pumping mechanism 38 is actuated by the engine throttle linkage and is effective to supply the nozzles 42 with an additional charge of fuel to facilitate rapid acceleration.

A throttle valve element 56 is disposed within each of the intake conduits 24 on the downstream side of the air atomizing nozzle 42 for the purpose of regulating the rate of supply of combustible mixture to the individual engine cylinders. An intake manifold vacuum conduit 58 extends from at least one of the intake conduits 24 on the downstream side of the associated throttle valve element 56 to the load sensor unit 34 as indicated. A fuel drain line 60 extends from a portion of the load sensor unit 34 to one of the air intake ports of the fuel and air pumping unit 32.

A branch conduit 62 extends from the conduit 50 for the purpose of transmitting a fuel pressure on the downstream side of the load sensor unit 34 to the speed sensor unit 44. A bypass conduit 64 extends from the fuel delivery conduit 46 to the above-mentioned starting unit 36 and another conduit 66 is provided for connecting the outlet side of the starting unit 36 to the fuel conduit 50. By preference, a suitable T type connection 68 is used for interconnecting the conduits 50, 62, and 66. The bypass conduits 64 and 66 are adapted to accommodate an auxiliary flow of fuel from the fuel and air pumping unit 32 to the individual or atomizing nozzles 42 during the engine starting operation, and the starting unit 36 is adapted to regulate the rate of flow of this additional fuel to that which is required to initiate and to maintain combustion during starting.

V Referring next to Figure 2, we have illustrated in more particular detail, the construction of the starting unit 36. The starting unit 36 comprises a body portion 70 formed with a first bore 72 within which an idle metering unit 74 may be disposed. The idle metering unit 74 comprises an insert 76 having an axially extending opening therethrough as shown at 78. A metering orifice means 80 is disposed within the internal opening 78 and an 4 adjustable metering element 82 may be axially positioned within the orifice means 80 in registry therewith. The metering element 82 is carried by a manually adjustable stem 84 which may be threadably received within the opening 78 and which may include an outwardly extending portion 86 to accommodatea suitable hand tool or the like. By preference, the metering element 82 is formed with a tapered opening at the extreme end 88 thereof, said tapered opening cooperating with the orifice means 80 to provide a variable restriction as the shank portion 84 is adjusted axially within the opening 78. The insert 76 may be retained in place by means of threads 90 formed on one portion of the outer periphery thereof and on a portion of the interior of the bore 72. Suitable O-ring type seals may be provided as shown at 92, 94 and 96 for the purpose of etfectively sealing the insert 76 and the shank portion 84 of the adjustable metering element The bypass conduit 64 is secured to the body portion 70 of the starting unit 36 by a threaded fitting 98 and it communicates with the central opening 78 of the insert 76 through ports 100. The bypass conduit 66 is secured to the body portion 70 by means of a suitable fitting 102 and also it communicates with the bore 72 as shown.

A second bore 104 is formed within the body portion 70 of the starting unit 36 and it also contains a hollow insert as shown at 106. This insert 106 may be identical in construction with the above-described insert 76 and it may include a metering orifice 108 Within which a metering element 110 is adjustably positioned. The metering element 110 may be identical in construction to the previously described metering element 82 and it may be adjusted by manually rotating the metering element shank portion 112.

A bypass passage 114 is provided for interconnecting the bore 72 with the bore 104, and ports 116 are provided for interconnecting the conduit 114 with the interior of the insert 106.

A reduced diameter portion of the bore 104 is shown at 118 and it is adapted to receive a hollow insert 120 having an orifice 122 formed at one end thereof as shown. A metering element 124 is positioned within the hollow insert 120 in registery with the metering orifice 122, and it is carried by a guide member 126, said guide member being telescopically received within the hollow insert 120. A radially extending flange 128 is carried at the upper end of the guide member 126 and is positioned on the exterior of the body portion 70. A plate 130 is secured to the body portion 70 by means of bolts 132 and it is provided with a recess 134 for receiving the flange 128, said flange being adapted to move vertically within the recess 134. A spring 136 is interposed between the plate 130 and the metering element 124 for normally biasing the latter in a downward direction so as to restrict the metering orifice 122. A solenoid 138 may be secured to the plate 130 in substantial alignment with the guide element 126 and it may be enclosed by a suitable housing 140, the latter being secured to the body portion 70 by bolts 142. Suitable means may be provided for energizing the solenoid 138 with engine ignition current when the engine operating temperatures are below a predetermined optimum value thereby causing the metering element 124 and its associated guide element 126 to move vertically upward, as viewed in Figure 2, thereby opening the flow metering orifice 122 to accommodate a greater flow of fuel therethrough. When the engine reaches a predetermined operating temperature, the solenoid 138 becomes deenergized and the metering element 124 is returned to its flow restricting position under the influence of the spring 136. A bimetallic'thermostatic switch or some other temperature responsive switch means may be used in a conventional manner for selectively controlling the flow of ignition current through the solenoid 138. An additional bypass passage 144 and an orifice 146 in the insert 120 provide communication between the interior oi -the element=120 and-the previously described-bore 72; It wit-1 therefore, :be apparent .that :the' flow of.:fue1-from the conduit 64 -throughrthegbore 72 and intothe conduit 66'will'be supplemented by "an additional bypass flow through-the bypass passage 114,-the port 116,-orifice 108, bore 104;orifice '122,-ports-146-, and the bypass passage 144: Howevergthis bypass fiowis obtained only when the engine operatingtemperatures arebelowthe predetermined optimum value as above explained.

A third bore 147 is provided withinthe housingbody portion 70 and it is adapted to receive aninsert 148 within which is formed a flow'metering ,orifice 150, the bore l47 communicating with the bore 104 in the interior ofrthe-insert-106 as-indicated. A'flow metering element 152 is slidablyreceived withintheinsert 148 in registry with theorifice -150 and-.it'includes a large diameter portion 154'and'a transverse fiange portion 156, the former accommodating a spring/for normally biasing-the flow metering'element'152 toward the left, as viewed in Figure 2, and the latter being situated within recess 158 formed in aside plate1-60 secured to the body-portion 70 by bolts 162. A solenoid element 164: is'secured to theplate 162 insubstantial alignment with the flow metering element 152 and it isenclosed by a suitable housing 166- which may: be secured to the body portion '70 by a bolt 168. Suitable means may be provided for energizing the sole noid element 164 with ignition currentas. the engine starter switch is closed thereby causing the metering .ele; ment 152 to move totheright, as viewedin Figure 2, during the cranking operation of the engine. The bore 146-comn1unicates with the bore 104' on the downstream side of the orifice 108 by means of intersecting passages .170 and 172 passage 170 communicating with the interior of the insert 148 'by means of ports 174.

Iri operation the restriction provided bythe orifice 80 may be manually adjusted so as to provide an idle bypass flow of a predeterminedmagnitudel It will be apparent from the schematic view of Figure 1 that this idle bypass flow supplements the flow of fuel through the speed sensor unit 44 and the load sensor unit 34, and when the fuel injection system is used with a conventional automotive type'engine, it is desirable to regulate this idle bypass fiow to a value approximately equal to 4 lbs. per hour. During the warm up period for such an engine, the flow metering orifice 122 will be'opened and an additional flow of approximately 2 lbs. per hour will be bypassed therethrough, the flow metering element 110 being manually adjusted with respect to the flow metering orifice 108 to accommodate the additional flow required. During the engine cranking operation it is desirable to provide an additional flow of approximately 20 lbs. per hour and the flow metering orifice 150 is accordingly'adapted to accommodate such a flow as the metering element 152 is moved to the right by the solenoid control 164. It will be observed that the metering orifice 122 is located on the downstream side of each of the. orifices 108 and 150 so that the additional bypass fiow during the warm up period and during the engine cranking operation is not obtained while the engine is warm.

Referring next to Figure 3, we have shown a cross sectional view of the load sensor unit for the above-described fuel injection system andit comprises a first housing portion 176 and a second housing portion 178, said housing portions being separated by a gasket 180; Suitable bolt means or the like may be provided for clamping the housing portions 176 and 178 together. The lower housing portion 176 is provided with a central chamber'182 and an opening 184 extends from the chamber 182 to theexterior of the housing portion 176. A hollow insert 186 is positioned within the opening 184 and is threadably retained therein by means of threads 188. A flow metering orifice 190 is formed at the inner. end of. the insert 186 and a tapered'metering element-192 is positioned within the hollow interior of theinsert 186 in registry with the new meteringsorifice 19.0.; Suitable seals-194 may be 6 provided 'for'preventing"leakingijbetween :the insert 186 andthe bore 184- A'fuel passage 200is formedin the housingtportion 176 and an intersecting passage 202 is formed in the housing portions 176 and 178, asshowmsaidpassage 202 communicating with-thefuel conduit 48"which' extends from the speed sensor unit 44 as previously described, a suitable fitting 204: being provided for this purpose.- The passage 200-communicates with the interior of the hollow insert 186- through ajport 206; By preference, a second pair of intersecting-passages-200'- and 202. may be provided in another location within the housing portions 176 and 178, said passages also communicating with the fuel conduit 48- to provide a secondsfuel delivery path.: Thefuelconduit 50, previously described, communicateswith thecene tral chamber 182througha port 206, a suitable.fitting.208 being provided to effect a suitable connection betweenthe port'206 and the conduit 50.

The housing portion 178 is formed with a hollow extension 210 within which is slidably. disposed a piston memher 214. A Theextremity of the extensiona210 threadably receives a closure member 216. which inturn threadably receives a fitting 218 for etfecting a connection with the vacuum conduit 58, previously described.

The piston 214 carries a shaft element 220 on one side thereof and it .is slidably received through. a bushing: 222, the-latter being inserted in an opening 224 extending from the central chamber 182 tov the interior of the housing extension 210. By preference, the-tapered metering ele.- ment 192 iscarriedby the extremity of the shaftelement 220 as indicated, and is adjustably positioned with respect to the meteringorifice 190 as the piston 214=is moved with respect to the extension 210. A pairof springs, as shown at 226 and at 228, are interposedbetween the piston 214 and the closure member 216, .the spring 228 havinga lower spring. rate thanthe spring 226. The spring 228 urges the piston 214 away from the closure member 216 throughout the entire operating stroke of the piston 214' while the spring 226' becomes unseated throughout a portion of the operating stroke of the piston 214, the free height of the spring 226 being less than the axial length of the hollow interior of the housing extension 210.

The drain conduit 60 communicates with the hollow interior of the piston extension 210 and it is adapted to accommodate any leakage of fuel past the bushing 222.

The chamber within the hollow extension .210 on one side of the piston 214 communicates with the ambient air through a vent 230.

During operation of the engine, a variation in engine load will be accompanied by a variation in the intake manifold vacuum pressure which in turn is communicated to the hollow interior of the housing extension 210 through the vacuum conduit 58. An increase .in manifold vacuum will cause the piston 214 to move against the biasing force of the springs 226' and 228 so as to restrict the flow of fuel to the metering orifice 190, thereby reducing the rate of fuel delivery to the air atomizing nozzles42. Upon an increase in load, the manifold vacuum decreases which in turn causesan increase in the fuel delivery rate.

' With an engine of the type. previously described, the manifold pressure varies non-uniformly with changes inthe power delivered by the engine, and it is therefore imr portant that the load sensor unit 34 should accordingly vary the rate of fuel delivery so as to meet the fuel re quirements of the engine over the entire operating range of the engine. For example, when the engine output power varies from of maximum to approximately 50% of maximum, thevariation in engine intake manifold. pressure may vary only about 3 inches. of mercury. However, a variation in the power outputfor the engine from approximately 50% of maximum to a is accompanied by a variation in the intake :manifold pressure of about-15 inches ofmercury. .Eorrthis reasom the lower rate spring 228 is employed for biasing the piston 214 asthe engine output power varies from a maximum to approximately 50% of maximum. As the engine output power varies from approximately 50% of maximum toa minimum, both of the springs 226 and 228 are employed for biasing the piston 214. The effective spring rate for both of the springs 228 and 226 therefore varies in magnitude from a lower value in the high power output operating range to a higher value in the lower power output operating range. Consequently, the position of the metering element 192 varies substantially linearly with the engine power output.

The operation of the load sensor unit is illustrated by the semi-logarithmetic diagram of Figure 3A wherein curve 1 represents a generalized relationship between the absolute manifold pressure and the percentage of the total engine power being delivered for a given constant engine speed. Curve 2 represents the variation in the opening or orifice 190 and correspondingly of fuel flow therethrough for various manifold pressures throughout the movement of piston 214 that is opposed solely by spring 228. Curve 3 similarly represents the extent of opening of orifice 190 and the flow of fuel throughout the movement of piston 214 that is opposed by both springs 226 and 228. The combined curves 2 and 3 closely approximate curve 1 so as to compensate adequately for the latters non-linear characteristics, whereby the rate of fuel delivered to the engine is at all times approximately equal to the fuel required at any given manifold pressure.

Referring next to Figure 4, we have illustrated the details of the construction of the speed sensor unit 44 and it includes a pair of juxtaposed housing portions 232 and 234 which may be secured together by bolts 236. Each of the housing portions 232 and 234 are provided with recessed interiors which cooperate to define a central chamber 238. A flexible diaphragm 240 is disposed transversely across the chamber 238 and is secured about its periphery between the juxtaposed surfaces of the housing portions 232 and 234 so as to define a pair of opposed chambers identified by the numerals 242 and 244.

One side of the housing portion 232 is recessed, as shown at 246, and a ring member 248 is seated within the recess 246, said ring member being secured to the housing portion 232 by screws 250. A second flexible diaphragm 252 is transversely disposed across the central opening of the ring 248 and is secured about its periphery between the juxtaposed surfaces of the ring 248 and the adjacent housing portion 232. The diaphragrns 252 and 240 are joined together for operation in tandem by a shaft 254. A pair of backup plates 256 and 258 are carried at one end of the shaft 254 and are secured thereon by a set screw 260. Similarly, a pair of diaphragm backup plates 262 and 264 are carried by the other end of the shaft 254 and are secured thereon by a suitable set screw 266. The housing portion 234 is provided with a central threaded aperture 268 within which a hollow metering insert 270 is threadably received. A flow restricting orifice 272 is formed in the metering insert 270 and a metering element 274 is slidably received within the hollow interior of the metering insert 270, said metering element 274 being adapted to register with the metering orifice 272 for controlling the degree of restriction thereof. A fitting 276 is threadably received over the end of the metering insert 270 to facilitate a connection with the fuel conduit 46 previously described, and a spring 278 may be interposed between the fitting 276 and the metering element 274 for biasing the latter toward the metering orifice 2721. The metering element 274- includes an extension 280 which extends through the orifice 272 and centrally contacts the end of the shaft 254.

The chamber 242 within the housing portion 234 communicates with the above-described fuel conduit 48, a suitable fitting 282 being provided for this purpose. Simi- 8 larly, the chamber 244 within the housing portion 232 communicates with the above-described conduit 62, another suitable fitting 284 being provided for this purpose.

A housing extension 286 is bolted on one side of the housing portion 232 and it encloses a speed governor mechanism generally designated by numeral 288. The governor mechanism 288 includes a pair of centrifugal counterweights 290 and 292 which are respectively pivoted at 294 and 296 to a carrier 298, the latter being secured to a supporting shaft 300. A shaft extension 302 extends from the shaft 300 toward the diaphragm 252 and it slidably carries a sleeve member 304. A flange 306 is formed at one end of the sleeve member 304 and the other end thereof is adapted to contact the screw 260. The shaft 300 is rotatably journalled in the housing extension 286 by means of bearings 308 and 310, the latter being engaged by a spacer element 312. By preference, a seal 314 may be provided as shown for containing bearing lubrication within the housing extension 286. The shaft 300 is formed with a reduced diameter portion 316 over which a sleeve member 318 is received and a pin 320 is provided for securing the sleeve 318 and the shaft portion 316 together. A flexible cable 322 may be secured at one end thereof to the sleeve 318 by a suitable key 324 or by any other suitable fastening means, the other end of the cable may be powered by the engine crankshaft in a conventional manner.

In operation, the engine driven cable 322 is effective to notate the carrier member 298 and the centrifugal weights 290 and 292 within the housing extension 286. Upon an increase in speed, the sleeve 304 is moved to the left, as viewed in Figure 4, by reason of the engagement of the flange 306 with notches 326 and 328 formed in the centrifugal weights 290 and 292. Upon movement to the left, sleeve 304 biases the diaphragm shaft 254 to the left thereby causing the metering element 274 to move to the left against the opposing force of the spring 278. This decreases the degree of restriction of the fuel metering orifice 272 thereby providing an increased flow of fuel to the fuel conduit 48.

As illustrated in Figure 4A, the arrangement and location of the center of gravity, C.G., of each of the weights 290 and 292 with respect to its pivot axis 294 or 296 and its notch 326 or 328 is important for proper functioning of the speed sensor device at all engine speeds. The centrifugal force acting through the centers of gravity and depending to pivot the weights 290, 292 about their pivots 294, 296 is pnoportional to the square of the engine speed which determines the speed of rotation of the shaft 322. When the center of gravity of each weight 290 or 292 is at an intermediate position on a line parallel to the axis of rotation of the shaft 300 and passing through the corresponding pivot axis of the weight, the centrifugal force leverage urging axial movement of sleeve 304 is a maximum. This leverage decreases as the center of gravity moves in either radial direction from the aforesaid intermediate position. It has been found that unless the extreme range of movement of the centers of gravity from their intermediate position is comparatively small, the centrifugal force leverage urging the sleeve 304 axially will be too great at low engine speeds in comparison to the corresponding leverage at high engine speeds. In order to obtain adequate fuel for high speed engine operation in such a situation, the speed sensor mechanism must be over-compensated to deliver excess fuel at low speeds.

The present construction overcomes the foregoing difficulty by the arrangement of the weights 290 and 292 shown wherein the centers of gravity at the extreme limits of movement are adjacent and spaced by their aforesaid intermediate positions. Radially outward swinging !Of the weights 290, 292 beyond the solid line position shown in Figure 4 is limited by abutment of the outer generallyradial shoulders of the weights at their right hand ends-with -the radial b'aseof the carrier-298w Radi allytinward swinging-cf the-weights beyoiidthe dotted position shown in Figure 4A islimited by abutment' 'of theirradial inner 'edges witlrsleeve'304." Within "the range of movements of the weights 290, 292 betweenthe solid line position-"(maximum fue1' delivery) and the dotted line position (minimum fuel delivery) thecentn'fugal force leverage urging leftward axial moveriientof sleeve 304 is substantially constantand at its maximum. Within this range however the" axial-displacement of the sleeve'304 for a given swinging movement of the-weights 290, 292 is a minimum. Movement of -the sleeve 304 to effect adequate movement of the metering element-274 is-- achieved with the structure shown by*maintainiirg the lever armlength A fromeachpivot 294 or 296'to'th'e corresponding notch 326px 328, greater, than 'thc'lever arm length B'from each pivot 294 r296 tothe-cor respondingrcenter inf-gravity. Thus any given swinging movementof the centers ofgravity about their 'pivots 294 and- 296 is magnified and converted to axial'movement of the sleeve 304.

Byvirtue of the arrangement of the 'centers' of gravity on leverarms B, which are shorter thanth'e lever arrns A- and which are pivotal outwardly and inwardly of the above-defined intermediate positions located on lines through the pivot axes 294, 296 and parallel to the axis of -rotation of the governor means, axial movement of the sleeve 304 is approximately directly proportional to' the swinging movement of the weights290, 292 though out-the entire operating speed rangeof the engine; Also the; leftward axial force exerted by sleeve304 urging diaphragm 240 leftward in Figure 4 and-openingorifice 272 is-approximately proportional to thesquareof the engine speed, so that proper fuel delivery is accomplished throughoutsubstantially "the entire enginespeed range.

Referringnext to Figures 5 through 8, we have disclosed a fuel or pumping'unit which is particularly adapted to be used with the fuel injection system herein disclosed, and it-comprises an intermediate housing por-' tion 330, an upper housing portion 332,an'd a lower housing portion 334. The upper surface of :the inter mediate housing portion 330 is recessed,-as shown at 336, and the lower portion of the upper housing portion 332 is recessed, as shown at 338 Each of the recesse's336 and 338 define separate'air pumping chambers which are separated by a flexible diaphragm memher 340, said diaphragm member340 being secured about its periphery between the juxtaposed surfaces of the upper housing portion 332 and the intermediate housing portion 330. Screws 342 may be provided forsecuring the upper housing portion 332 in 'place as shown. A pair of diaphragm backup plates 344 and 346 is disposed on either side of the diaphragmmember340 and a vertically disposed shaft 348 is secured centrallyto the backup plates 344 and 346-as shown. An air-diaphragm spring 350 is interposed between the backup plate 344' and the interior of the housing :portion'332'for biasing the'diaphragm 340 in a downward direction.

As best seen in Figure 5, the upper housing portion 332 isprovided with an inlet and outlet passagei'shown at-352 and 354 respectively. A port 356' may beprovided in the upper housing portion332 toprovide communication between the outlet passage354' and the above mentioned air passage 54; Similarly, a port 358 may be provided in thehousing portion 332' to provide communication between the inlet port 352 and the drain passage 60, said drain passage being adapted to accommodate the flow of inlet air to the'working chamber defined by the recess-338.

Referring next to Figure 6, we have shown in more particular-detail the construction of the inlet andou'tlet air pas- sages 352 and 354 and they each include-a check valve 'device to accommodate a one-way flow of 1 air the'rethrough.' The checkvalve'associated' with passage 352: includescani:apertured plate360 and a muvauevalve plate 362 i which selectively opens and closesthe apertures of the plate 360: An open cage 364 isprovided for containing the movable valve plate 362 and'a -retainerpin 366 may be provided as indicated for securing the'cage-364-to' the apertured plate 360. The check valvev associated with the outlet air'passage'354 is similar'in construction to the check valve described above and it includes an apertured 1 plate 368 disposed transversely across-the passage 354, a movable plate 370 and a cage 372, the latter being secured to the plate 368 by a retainer pin 374.

Referring next to Figures 7 and-8, a check valve housing 376 is secured to the" intermediatehousing porti'on 330- below the air-working chamber defined bythe recess 336; An inlet air passage and an outlet airpassage are formed in the housing 376, asshown at 378 and 380 respectively, the-former communicating with a suitable air inlet connection, not specifically shown, and the latter communicating with 'the'air delivery conduit 52,-'-ports- 382- and 384 being provided forthis purpose-1- Each of-the passages 378 and 380 includes a one-way check valve mechanism generally designated in Figure 7 by-num'eral 386, eachof said mechanisms being similar to tho'seillustrat'ed in Figure 6.

The lower portion'of-the intermediate housing portion 330 includes a spring chamber 388 across which a fuel diaphragm 390 is'disposed. The lower housing portion 334' is recessed at 392 to define a fuel working chamber below the fuel diaphragm- 390 and the periphery of the diaphragm 390 is secured between the juxtaposed surfacesof the'housing portions 330*an'd 334'. A fuel outlet passage 394 is formed within thehousing portion-334' and it is adapted to' be connected to fuel delivery conduit 46, previously described. A suitable fuel'inlet passage for the fuel working chamber 392 may also be provided for maintaining a supply of combustible fuel within the fuel working chamber. The fuel inlet and outlet passages for the fuelwork ing chamber may be formed with suitable one-way check valve mechanismsof known construction.

A pair of backup plates 396 and 398 are disposed on either side of the-fuel diaphragm 390 and an actuat ing shaft 400' is centrally secured thereto as shown. A fuel spring 402 is disposed within the spring chamber 388 and it is eifective'to bias the fuel diaphragm 390," as viewed in Figure 7. The actuating shaft 400 extends vertically upward into a transverse opening 404 formed in the intermediate housing portion 330. An operating lever 406 is pivoted at 408 within the opening 404 and it is connected to the actuating shaft 400a: the inner end thereof'bymeans of a lost motion connection generally designated by numeral 410. The inner end of the lever 406 also engages the air diaphragm actuating shaft 348 to'- provide a one-way mechanical connection between lever 406 and shaft 348. As the lever 406 is rotated in a clockwise direction, the fuel diaphragm actuating shaft 400 is moved with an upward intake stroke and the" air diaphragm actuating shaft 348 is simultaneously moved upwardly to provide a compression stroke for the upper air working chamber and an' air intake stroke for the lower air' workingchamber. Upon movement of the lever 406' in a counterclockwise direction, the air spring 350 moves the air diaphragm 340 ina downward direction to provide an air intake stroke for the air working chamber defined by recess 338 and a compression 'strokefor the air Working chamber defined'by recess 336. Similarly, the fuel spring'402 biases the fuel diaphragm-390 in a downward direction to provide a Working stroke for the fuel working chamber defined by recess 392. The lever 406 may be actuated'by a suitable cam connection with the engine crankshaft; one-end of the lever 406 being provided-with a cam follower" element 41 2-for thispurpose.

Referring next to Figure 9,- the accelerator pumping mechanism 38 includes a central cylindrical housing portion 414 and two end housing portions '416 and 418. A working diaphragm 420 is disposed transversely across one end of the intermediate housing portion 414 and is secured about its periphery between the juxtaposed sur faces of the housing portions 414 and the end housing portion 416. Similarly, a sealing diaphragm 422 is transversely disposed across the other end of the intermediate housing portion 414 and is secured about its periphery between the intermediate housing portion 414 and the end housing portion'418. A transverse wall 424 is disposed across the interior of the housing portion 414 and is adapted to slidably receive the diaphragm actuating shaft 426. A check valve mechanism 428 is provided for accommodating the unidirectional flow of fuel from the chamber defined by the wall 424 and the sealing diaphragm 422 to the working chamber defined by the wall 424 and the working diaphragm 420. The chamber which is partly defined by the sealing diaphragm 422 is in fluid communication with the above-described fuel condit 41, a suitable fitting 430 being provided for this purpose. Similarly, the working chamber partly defined by the working diaphragm 420 is in fluid communication with the above-described fuel conduit 43, a suitable fitting 432 being provided for this purpose. The diaphragm actuating shaft 426 may be connected to the engine accelerator linkage mechanism by means of a lost motion connection, and upon movement of the throttle valves toward an open throttle position, an accelerator pumping spring, not shown, may bias the diaphragm actuating shaft 426 toward the right, as viewed in Figure 9, thereby causing a charge of fuel to be delivered to the fuel conduit 43 into the fuel delivery conduit 50 and the nozzles 42. The check valve 40 between the conduits 43 and 50 is effective to prevent this auxiliary charge from entering the fuel outlet port or the load sensor unit 34 and for preventing a return flow of fuel from the conduit 50 into the conduit 43.

During operation of the engine, the rocker arm 406 of the fuel and air pumping unit 32 is adapted to be actuated by the engine camshaft thereby causing the fuel and air diaphragm to' become deflected. The air pumping portion of the pumping unit 32 is double acting, the air diaphragm being positively controlled in the upward direction and spring biased in the other direction. The working stroke of the fuel pumping portion of the unit 32 is single acting and the pumping stroke takes place by virtue of the force exerted by the fuel spring 402.

Upon an increase in engine load while the engine speed remains constant, the engine manifold pressure increases, and therefore the piston member 214 of the load sensor unit 34 is urged in a downward direction to increase the effective opening of the metering orifice 190. This tends to increase the total flow through the load sensor unit and to decrease the pressure drop across the metering orifice 190. This pressure drop is transmitted across the diaphragm 240 of the speed sensor unit which in turn causes the metering element 274 to move away from orifice 272 and to increase the effective opening of the latter. This in turn results in an increased fuel fiow to accommodate the increased fuel requirements, and since the rate of flow of fuel through the orifice 190 of the load sensor unit is correspondingly increased, the pressure drop across the orifice tends to increase to that value which existed before the engine load was changed. Thus, the pressure drop across the diaphragm 240 of the speed sensor unit is not affected by variations in engine load. The dimensions of the tapered metering element 192 of the load sensor unit are chosen so as to make this characteristic possible. 7

Further as explained above, the characteristics of the governor mechanism 288 of the speed sensor unit are such that the net axial force exerted on the sleeve 3G4 and diaphragm shaft 254 by the weights 290 and 292 will remain substantially constant for any given speed of rotation regardless of the radial position of the weights 290 and 292 or the axial position of the diaphragms 240 and 252. This axial force will result from the centrifugal force on the weights 290 and 292 and will thus be a direct function of the engine speed which determines the speed of rotation of the weights 290 and 292.

It will be apparent from the foregoing description that the unique construction of the speed sensor unit 44 does not require a complex sealing element for containing the fluid within the chamber on either side of the diaphragm 240. The need for a seal about the diaphragm shaft 254 is completely eliminated since it does not extend through a stationary wall of the pressure chamber partly defined thereby. The provision of a sealing diaphragm 252, as described, effects a completely enclosed fluid chamber and the net biasing force exerted by the metering element 274 is equal to the pressure force on diaphragm 240 less the pressure force on diaphragm 252. Such a construction greatly increases the sensitivity and reliability of the unit.

In addition, the compact and concentric arrangement of the constituent elements of the speed sensor unit 44 makes the same simple to construct and assemble and readily adapts the same to be used in commercial fuel injection systems.

What we claim and desire to secure by United States Letters Patent is:

1. In a fuel control system for a liquid fuel engine having a fuel pressure source and a fuel delivery conduit extending from said source to said engine, an engine speed sensitive fuel metering unit including a fuel metering orifice forming a portion of said fuel delivery conduit, a movable fuel metering element registering with said orifice for progressively restricting the latter upon movement thereof, a first flexible diaphragm disposed within said unit and partly defining a first fuel chamber therein, said orifice communicating with said first fuel chamber, said metering element being adapted to be actuated by said first diaphragm, a second sealing diaphragm coupled to said first diaphragm and disposed adjacent thereto, said first and second diaphragms defining a second fuel chamber, said second fuel chamber communicating with said fuel delivery conduit at a downstream location, and a speed governor means having portions within said unit for deflecting said coupled diaphgr-ams to vary the degree of restriction of said metering orifice.

2. In a fuel control system for a liquid fuel engine having a fuel pressure source and a fuel delivery conduit extending from said source to said engine, an engine speed sensitive fuel metering mechanism including a housing, a fuel metering orifice in said housing forming a portion of said fuel delivery conduit, a movable fuel metering element registering with said orifice for progressively restricting the latter upon movement of said metering element, a first flexible diaphragm in said housing partly defining a first fuel chamber on one side thereof, said first fuel chamber communicating with said orifice, said metering element being adapted to be actuated by said first diaphragm, a second flexible diaphragm in said housing, means for coupling said first and said second diaphragms together for operation of the same in tandem, said first and second diaphragms defining a second fluid chamber therebetween, passage means interconnecting said second fuel chamber with said fuel delivery conduit at a location downstream from said fuel metering orifice, the fuel pressure differential between said first fuel chamher and said downstream location being effective to urge said coupled diaphragms in one axial direction, and engine speed responsive governor means for biasing said coupled diaphragms in the other axial direction with a force which is a function of engine speed.

3. In a fuel control system for a liquid fuel engine having a fuel pressure source and a fuel delivery conduit extending from said source to said engine, an engine speed sensitive fuel metering mechanisms including a housing'r-a fuel metering-verifier: in said housing: forming a portion of said fuel delivery condiut,-- amovablefuel metering relementregistering-;;with said orifice for progressively restricting the latter upon movement ofsaid metering :elemen't, afirsr-fiexible diaphragm in said housing partlydefiningqa first fuel chamber on one-side thereof,-.i' said?first-fuel chamber communicating with saidorifice, said metering element being adaptedto be actuated by3said first diaphragm;v a second'flexiblediaphragm in said housing-,v-means: for. couplingysaid first and said secondcdiaphragms together for-operatiomof thesame in tandem, said--first and -second1 diaphragms defining a second fluid ichamber therebetween,- passage means interconnectin'g said second=fuel chamber with said fuel delivery :conduit at: a locationdownstream from said fuel metering: gorifice; the fuel" pressure differential between said first fflll :chamber and said downstreamlocation being eifectiveto urge saidcoupledrdiaphragms' in one axial: direction, 2 and engine speed responsive governor meansrfor actuating saidcoupled diaphragmsin the'other. axial# direction, said governor'means' including an axially movableazelemenh for engaging and actuating said diaphragm COHPlllJguIllfiflllSgmfill adaptor rotatably mounted within-said housing andcentrifugal weights carried by said adaptor, said centrifugal-weightshaving portions engageable; with said raxiallymovable element; v,4.Th'e combination -asset forth in claim 3 whereinsaid secondrdiaphragrncis substantially smaller than'said first: diaphragmandwherein the characteristics of said governor mechanism? are suchthat the axialforce exerted upon said-axially. movable element is substantially constant at a given engine speed rega'rdless' of theaxial' position of said axially movable element.

5. The combination-as set forthin claim-'4 wherein said first and second diaphragms, said axially movable element,- andsaidcentrifugal-,weights are coaxially arranged-.7,

;.6. -In-a .fuel injection system for an engine having at least-oneengine cylinder with-an intake manifold condui-bcommunicatingiwith said cylinder, said system in cluding a low pressure 'liquid fuel air atomizing nozzle means'for-supplyingisaid intake conduit witha combustiblevcharge of=atomized fuel, a low pressurefuel andairpumpingunit for.-supplying' said nozzle with'liquid fuel andwfuel atomizing;air,r.and separate conduit means for -conductinggboth liquid fuel andairto said nozzle; an engine speed sensitive metering-mechanism comprisingna fuel metering-orifice disposed inua portion of said fuel conduit means'andanengine-load responsive meteringvmechanism" disposed in saidv fuel conduit means on thedownstreamside of said metering orifice, said engine speedresponsive metering mechanism includnig a housing,-';:; amovable fuel. metering element registering with said-.orificelfor progressively restricting the latter upon movement thereof, a first flexible diaphragm in said; housing ,partly d'efinin'gga first-fuel chamber on one side thereof, saidfirst:fuelrchambericommunicating with said orifice-said metering element being adapted to be acmated by :said--first: diaphragm, a tsecond flexible di'a phragmdn: said-housing; means for-coupling said first. and said second diaphragms together: for operation ofthe samet in tandem, said first'and second diaphragms defin in'gia second fuel, chamberitherebetwe'en, said first fuel chamber forming: a portion of: said fiuidconduitmeans intermediate saidmetering orifice-and said load responsive metering: mechanism; said second fuel chamber com-- municatingwithsaid fluid conduit means on the downstream side of said load: responsive meteringmechanism; thevfuel pressuredifferential across said load respon-. sivermetering mechanism being effective to bias said coupled diaphragms'in one axial direction, and an enginespeed r'esponsivegov'ernor meanszfor biasingsaid coupled diaphragms in the :-other axial direction with a force which i'srafimction' ofenginefspeed;

7. In afuel injection system'foran engine having rat least one engine cylinder with an intake manifoldcom duit communicating with saidcylinder, said systemincludingralow pressure liquid fuel air atomizing nozzle means'for supplying said intake conduit with a combustible charge of atomized fuel, a low pressure fuel and air pumping unit for supplying said nozzle 1 with liquid fuel and fuel atomizing air, and separate conduitmeans f0r-c0nductii1g both liquid fuel and air to said nozzle; a speed sensitive metering imechanism comprising a fuel metering orifice disposed in a portion of said fuel conduit means and an engine load responsive metering mechanism disposed in said fuel conduit means on the down-' stream side of said metering orifice, said engine speed responsive metering mechanism including a housing,;.a movable fuel metering element registering with said orifice. for progressively restricting the latter upon mo vement thereof, a first flexible diaphragm in'said housingpartly defining a; first fuel chamber on" one side thereof; said-first fuel chambercommunicating' with said orifice, said metering element-being adapted to be actuated by said first diaphragm, a second flexible diaphragm in said housing, means for coupling said first and said second diaphragms together for operation of the same in tandem; said' first and second diaphragms defining a second fuel chamber'therebetween," said first fuel chamber forminga portion of said" fuel conduit'means intermediate said meteringiorificeand said load resp'onsivemetering mecha'e nism, said second fuel chamber communicating with saidfuel conduit means on the downstream side'of said load responsive metering mechanism, the fuel pressure dinerential': across said load responsive metering mechanism being effective to'bias said coupled diaphragms inbne axial direction, engine speed-responsive governor means" foriactu'ating said coupled diaphragms in the other axial direction, said governor means including an axially movable element for engaging and actuatingsaid coupled diaphragms; an enginepowered adaptor rotatably mount ed within said housing; and centrifugal weights carried by said adaptor, said centrifugal weight's'having portions" engageable with said axially movable element.

8. The combinationas set forth in claim 7 wherein said-seconddiaphragm is substantially smaller than said first diaphragm, and wherein the characteristicsof said governor mechanism are such that the axial force exerted upo'n saidaxially movable element is substantially constant at a given engine speed regardless of the axial position of said axially movabl'e element.-

9; The' combination as set forth in claim 8 wherein said first" and said second diaphragm, said axially mov' able elementgand said centrifugal weights are'axiallyar'-' ranged. 7

l0. In a fu'elinjection system for a liquid fuel engine havinga fuel pressure source and a fuel delivery con duit extending from said source to said engine, an engine speed sensing metering mechanism including a housing;

a fuel metering orifice in said housing forming a -por-' t-ion of said fuel delivery conduit, a movable fuel metering'element registering with said orifice for progressively restricting: the latter upon movement of said metering element, a first fiexiblediaphragm in' said" housing partlydefining a first fuel chamber on one side thereof, said firstlfu'el chamber communicating with said orifice, a sec ond' flexible diaphragm in said housing, means for cou- 1 p1ing'isaid"first--and second diaphragms together for op citation" of the same in tandem, means for biasing said metering element in 'one direction toward a flow restricting' position with respect to said orifice, a portion of said metering element contacting said coupled diaphragms,

said diaphragms being adapted to urge said metering element in theopposite axial direction, said first and second diaphragms-defininga second fuel chamber therebetween;

p'assage'means interconnecting said second fuel chamber with said delivery conduit at a location downstream from saidrfuel -metering sorifice, the fuel pressure differential between said fuel chamber and said downstream location being effective to urge said coupled diaphragms in said one axial direction, and engine speed responsive governor means for actuating said coupleddiaphragms in said opposite axial direction, said governor means including an axially movable element for engaging and actuating said diaphragm coupling means, an engine powered adaptor rotatably mounted within said housing and centrifugal weights carried by said adaptor, said centrifugal weights having portions engageable with said axially movable element.

11. In a fuel injection system for a multiple cylinder internal combustion engine, said system including a low pressure, air atomizing, liquid fuel nozzle means for supplying the engine cylinders with a combustible charge of atomized fuel, a low pressure fuel and air pumping mechanism, separate fuel and air conduits interconnecting said pumping mechanism and said nozzles, and a first fuel flow restricting means located in said fuel conduit; an engine speed sensitive metering mechanism comprising an orifice disposed in and forming a portion of said fuel conduit, a metering element registering with said orifice, a flexible diaphragm partly defining a fuel chamber communicating with said orifice, a second diaphragm mounted adjacent said first diaphragm and defining a second fuel chamber, auxiliary conduit means interconnecting said second fuel chamber and said fuel conduit on the downstream side of said flow restricting means, said metering element being adapted to be actuated by said first diaphragm, and an engine speed responsive governor means for biasing said first diaphragm in an axial direction to cause a decrease in the degree of restriction of said orifice upon an increase in engine speed, the pressure differential across said fiow restricting means being effective to bias said first diaphragm in the other axial direction.

12. The combination as set forth in claim 11 wherein said diaphragms are coupled for simultaneous movement and wherein said governor means includes an axially movable portion engaged with said coupled diaphragm, an engine driven adaptor mounted for rotation about a central axis, and centrifugal weights carried by said adaptor, said weights being engageable with said axially movable portion and adapted to adjust the same upon a variation in engine speed, said metering element, said diaphragm, said axially movable governor portion, and said centrifugal weights being coaxially arranged.

13. In a fuel control system for a liquid fuel engine having a fuel source and fuel delivery conduit means extending from said source to said engine, an engine speed responsive fuel metering unit having a hollow portion, shiftable means partitioning said hollow portion into first and second fuel chambers and being adapted to be shifted by the force of a fuel pressure differential between said chambers, said first chamber comprising a portion of said conduit means and the latter including a fuel metering aperture upstream from said first chamber and communicating therewith to deliver fuel thereinto, a movable fuel metering element cooperable with said aperture for progressively restricting the same and being adapted to be actuated by said shiftable means, said second chamber communicating with said fuel delivery means at a location downstream from said first chamber, and engine speed responsive governor means having a shiftable portion, shiftable sealing means partially defining said second chamber, a shaft extending through said sealing means and operatively connecting the shiftable portion of said governor means and said shiftable means to shift the latter to vary the degree (pf restriction of said aperture as a function of the engine speed.

14. The combination according to claim 13 wherein the fuel pressure differential between said first fuel chamber and said location downstream is effective to urge said shiftable means and metering element in the direction tending to restrict said aperture, and said governor means is effective to urge said shiftable means and metering element in the opposite direction with a force which is a direct function of the engine speed.

15. The combination according to claim 14 and comprising in addition an engine load responsive fuel metering mechanism disposed in said conduit means downstream of said first fuel chamber, and said location downstream being downstream of said load responsive fuel metering mechanism. 7

16. In a fuel control system for a liquid fuel engine having a fuel source and fuel delivery conduit means extending from said source to said engine, an engine speed responsive fuel metering unit having a hollow portion, shiftable means partitioning said hollow portion into first and second fuel chambers and being adapted to be shifted by the force of a fuel pressure differential between said chambers, said first chamber comprising a portion of said conduit means and the latter including a fuel metering aperture communicating with said first chamber, a movable fuel metering element cooperable with said aperture for progressively restricting the same and being adapted to be actuated by said shiftable means, engine speed re sponsive governor means having a shiftable portion cooperable with said shiftable means and being effective to shift the latter to vary the degree of restriction of said aperture as a function of the engine speed, an engine load responsive metering mechanism disposed in said conduit means downstream of said first chamber and metering aperture, and fluid passage means connecting said second chamber with said conduit means at a location downstream from said load responsive metering mechanism effective to equalize the fuel pressure between said location and second chamber.

17. The combination according to claim 16 wherein said load responsive metering mechanism comprises a second fuel metering aperture defining a part of said conduit means, a shiftable pressure responsive member having one side exposed to the engine manifold pressure to be shifted thereby, a second movable fuel metering element operatively coupled with said member to be shifted thereby and being cooperable with said second aperture for progressively restricting the same, and resilient biasing means yieldingly urging said member and second metering element to a predetermined position, said biasing means having one spring rate throughout one range of movement of said member and having another spring rate throughout another range of movement of said member.

18. The combination according to claim 16 wherein said load responsive metering mechanism comprises a second fuel metering aperture defining a part of said conduit means, a shiftable pressure responsive member having one side exposed to the engine intake manifold pressure to be shifted thereby, a second shiftable fuel metering element operatively coupled with said member to be shifted in one direction or the opposite responsive toa decrease or an increase respectively in said manifold pressure, said second metering element and aperture being cooperable to restrict the latter progressively upon shifting of the former in said one direction, resilient means biasing said member to shift said second metering element in said opposite direction, said resilient means having one spring rate throughout one range of movement of said member responsive to a comparatively high manifold pressure and having a relatively higher spring rate throughout another range of movement of said member responsive to a lower manifold pressure.

19. In a fuel control system for a liquid fuel engine having a fuel source and fuel delivery conduit means extending from said source to said engine, an engine speed responsive fuel metering unit having a hollow portion, shiftable means partitioning said hollow portion into first and second fuel chambers and being adapted to be shifted by the force of a fuel'pressure differential between said chambers, saidifirst chamber comprising a portion of said conduit means and the latter including a fuel metering aperture upstream from said first chamber and communicating therewith to deliver fuel thereinto, a movable fuel metering element cooperable with said aperture for progressively restricting the same and being adapted to be actuated by said shiftable means, engine speed responsive governor meanshaving a shiftable portion cooperable 'with said shiftable means and being effec tive to shift the latter to 'vary the degree of restriction of said aperture as a function of the engine speed, a load responsive metering mechanism comprising a second fuel metering aperture defining a part of said conduit means, a shiftable pressure responsive member having one side exposed to the intake manifold pressure to be shifted thereby, a second shiftable fuel metering element opera'ti-vely coupled with said member to be shifted in one direction or the opposite responsive to a decrease or an increase respectively in said manifold pressure, said second metering element and aperture being coopera-ble to restrict the latter progressively upon shifting of the former in said one direction, resilient means biasing said member to shift said second metering element in said opposite direction, said resilient means having one spring rate throughout one range of movement of said member responsive to a comparatively high manifold pressure and having a relatively higher spring rate throughout another range of movement of said member responsive to a lower manifold pressure.

20. In a low pressure liquid fuel injection system for an internal combustion engine having an intake manifold and a plurality of engine cylinders, separate manifold portions extending to each engine cylinder, at liquid fuel nozzle mounted in each manifold portion, fuel delivery conduit means communicating with said nozzles, a load sensor unit having a fuel metering orifice defining a part of said conduit means, said load sensor unit further including a movable wall, a metering valve element registering with said orifice for progressively restricting the same, said metering valve element being operatively associated and movable with said movable wall, a vacuum passage extending from said load sensor to said intake manifold to subject one side of said movable wall to manifold vacuum pressure, said vacuum pressure causing movement of said movable wall and said metering valve element toward an orifice closing position, and spring means for biasing said movable wall and said metering valve element toward an orifice opening position, said spring means being characterized by a given spring rate during movement of said movable wall within a first range of positions and by another spring rate during movement of said movable wall in another range of positions whereby the variation in fuel delivery rate for a given speed and the variation in engine horsepower delivered for any given change in manifold pressure are substantially similar.

21. In a low pressure liquid fuel injection system for an internal combustion engine having an intake manifold and a plurality of engine cylinders, separate manifold portions extending to each engine cylinder, a liquid fuel nozzle mounted in each manifold portion, fuel delivery conduit means communicating with said nozzles, a load sensor unit having a fuel metering orifice defining a part of said conduit means, said load sensor unit further including a movable wall, a metering valve element registering with said orifice for progressively restricting the same, said metering valve element being operatively associated and movable with said movable wall, a vacuum passage extending from said load sensor to said intake manifold to subject one side of said movable wall to manifold vacuum pressure, said vacuum pressure causing move ment of said movable wall and said metering valve element toward an orifice closing position, and spring means for biasing said movable wall and said metering valve element toward an orifice opening position, said spring means including a first spring for biasing said movable wall during movement of the same within a given range of operating positions and a second spring for supplementing the biasing effort of the first spring during movement of said movable wall within another range of operating positions.

22. In a low pressure liquid fuel injection system for an internal combustion engine having an intake manifold and a plurality of engine cylinders, separate manifold portions extending to each engine cylinder, a liquid fuel nozzle mounted in one of said manifold portions, fuel delivery conduit means extending to said nozzle, an engine load sensor unit interposed in said conduit means, said load sensor including a metering orifice defining a part of said conduit means, a metering valve registering with said orifice for progressively restricting the same, a movable wall, said metering element being operatively associated and movable with said movable wall, means for applying an engine load signal in the form of intake manifold pressure to one side of said movable wall thereby causing movement of the same toward an orifice opening position, and a variable rate spring means for urging said movable wall toward an orifice closing position whereby the rate of change of fuel delivery to said nozzles for any given change in manifold pressure substantially corresponds to the change in engine horsepower delivered which accompanics such a change in manifold pressure.

23. In a low pressure liquid fuel injection system for an internal combustion engine, fuel delivery conduit means extending to said engine, an engine load sensor interposed in said conduit means, said load sensor includ ing fuel metering means defining a part of said conduit means and having a movable metering element, variable rate spring means for yieldingly urging said movable element toward a biased position, and means for applying an engine load signal to said movable element to actuate the same in response to engine load, thereby to vary the rate of fuel delivery to said engine in accordance with said engine load.

24. The combination as claimed in claim 23 wherein said spring means is characterized by a given spring rate during movement of said movable element within a first range of positions and by another spring rate during movement of said movable element in another range of positions.

25. The combination as claimed in claim 23 wherein said spring means has a comparatively high spring rate throughout one range of movement of said movable element corresponding to comparatively small engine loads and has a lesser spring rate throughout another range of movement of said movable element corresponding to comparatively larger engine loads.

References Cited in the file of this patent UNITED STATES PATENTS

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